1. Technical Field
The present invention relates, generally, to an impact signal processor for a front impact acceleration sensor, and more particularly to an impact signal processor for a front impact acceleration sensor which can reduce sensor noise and the influence of disturbances against an impact signal by filtering a signal from a front impact acceleration sensor using a signal from a vertical acceleration sensor built in an airbag controller.
2. Background Art
Typically, an airbag impact discrimination algorithm for operating an airbag when car impact occurs discriminates the existence/nonexistence of car impact based on a sensed signal from a vertical acceleration sensor built in an airbag control unit.
However, since actual car impact can be of various types, such as front impact, impact on an inclined surface, offset impact, impact into a center pole, or the like, such various types of impact cannot be discriminated by only the vertical acceleration sensor built in the airbag controller. Recently, front impact acceleration sensors have been additionally mounted on front parts of a vehicle, e.g. in the neighborhood of both headlights, and an airbag impact discrimination algorithm has been used to discriminate diverse types of impact using such sensors.
However, according to the impact discrimination algorithms currently used, although the vertical acceleration sensor built in the airbag control unit is given much weight, the data obtained from the front impact acceleration sensor is additionally used to discriminate the impact type. However, when the front impact occurs, the front impact acceleration sensor is first damaged or is greatly influenced by the external disturbance or noise, and thus the data obtained from the front impact acceleration sensor is not reliable without any separate signal process of the signal output from the front impact acceleration system.
FIG. 1 is a graph showing an exemplary speed signal ACU-Vx1 sensed though the vertical acceleration sensor built in the airbag control unit, a speed signal FIS-LH-Vx sensed through the left-side front impact acceleration sensor, and the speed signal FIS-RH-Vx sensed through the right-side front impact acceleration sensor when the actual front impact of a vehicle occurs.
When the front impact occurs, the two FIS signals, which are the same type, should exist below ACU-Vx1. However, since the right-side front impact acceleration sensor is damaged and is not in a normal operation state, as shown in FIG. 1, FIS-RH-Vx maintains the value of “0” for a predetermined time just after the impact, and then its slope is abruptly changed.
Accordingly, since there is a very high possibility that the front impact acceleration sensor is damaged by the vehicle impact or other external causes, it may be difficult to normally judge the impact if the signal output from the front impact acceleration sensor is used as it is.
Accordingly, in order to judge the impact type of the vehicle more accurately, a method capable of securing the reliability of data provided from the front impact acceleration sensors is needed in the art.
The above information disclosed in this the Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.